Exploring the impact of traumatic injury on mortality: An analysis of the certified cause of death within one year of serious injury in the Scottish population

Abstract

Background: Few studies effectively quantify the long-term incidence of death following injury. The absence of detailed mortality and underlying cause of death data results in limited understanding and a potential underestimation of the consequences at a population level. This study takes a nationwide approach to identify the one-year mortality following injury in Scotland, evaluating survivorship in relation to pre-existing comorbidities and incidental causes of death.

Study design: This retrospective cohort study assessed the one-year mortality of adult trauma patients with an Injury Severity Score ≥ 9 during 2020 using the Scottish Trauma Audit Group (STAG) registry linked to inpatient hospital data and death certificate records. Patients were divided into three groups: trauma death, trauma-contributed death, and non-trauma death. Kaplan-Meier curves were used for survival analysis to evaluate mortality, and cox proportional hazards regression analysed risk factors linked to death.

Results: 4056 patients were analysed with a median age 63 years (58-88) and male predominance (55.2 %). Falls accounted for 73.1 % of injuries followed by motor vehicle accidents (16.3 %) and blunt force (4.9 %). Extremity was the most commonly injured region overall followed by chest and head. However, head injury prevailed in those who died. The registry demonstrated a one-year mortality of 19.3 % with 55 % deaths occurring post-discharge. Of all deaths reported, 35.3 % were trauma deaths, and 47.7 % were trauma-contributed deaths. These groups accounted for over 70 % of mortality within 30 days of hospital admission and continued to represent the majority of deaths up to 6 months post-injury. Patients who died after 6 months were mainly the result of non-traumatic causes, frequently circulatory, neoplastic, and respiratory diseases (37.7 %, 12.3 %, 9.1 %, respectively). Independent risk factors for one-year mortality included a GCS ≤ 8, modified Charlson Comorbidity score >5, Injury Severity Score >25, serious head injury, age and sex.

Conclusion: With a one-year mortality of 19.3 %, and post-discharge deaths higher than previously appreciated, patients can face an extended period of survival uncertainty. As mortality due to index trauma lasted up to 6 months post-admission, short-term outcomes fail to represent trauma burden and so cogent survival predictions should be avoided in clinical and patient settings.

Keywords: 1-year mortality; Cause of death; Injury; Injury severity score; Major trauma; Mortality; Multiple injuries; Outcome; Severe injury; Trauma; Trauma registry.